The really interesting part is, they used a mix of advanced genic techniques to achieve this result. Firstly, the DNA of a defective cell is corrected with a gene first assembled in the lab. This procedure has always been very dangerous for the past 20 years: the fact that it can be used is a good achievement alone. Secondly, the corrected DNA is propagated in the patient body using a stripped-down version of the HIV virus, of which less than 10% of its original genome remains.